Does anyone know how MC gets the threads in the stringers for the motor mount bolts? Is it an insert or is there metal that is glassed in during construction that they drill and tap? Might do a test bore tomorrow, but was hoping someone could shed a little light on this for me. Thanks
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I'm not sure about the MC process, but I know that CC has the metal plates glassed into their preformed stringers. MC got into the foam stringer system way before CC, so they may have come up with a better way over the years.

I wish I had the answer for you, but I must say
1. Sounds like this project deserves it's own thread
2. Can you not make an adapter plate to allow you to utilize existing holes?

Going to start a new thread once I'm sure I can make this work. I did some pilot holes in the stringers, looks like the metal is laminated front to back. Whew, that's a plus! I can drill and tap at will. Lots of other stuff to figure out. Looks pretty cool no?